Nancyvarkey at 06:11, 18 December 2015

2015-12-18T06:11:56Z

Show changes

Gautam at 20:31, 7 August 2014

2014-08-07T20:31:49Z

Gautam at 07:55, 7 August 2014

2014-08-07T07:55:02Z

Show changes

Gautam: Created page with 'Tutorial: Creating and Meshing an airfoil in Gmsh Script and Narration: Gautam Sharma Keywords: Gmsh, Meshing, airfoil. {| style="border-spacing:0;" | style="border-top:…'

2014-08-07T07:48:21Z

Created page with 'Tutorial: Creating and Meshing an airfoil in Gmsh Script and Narration: Gautam Sharma Keywords: Gmsh, Meshing, airfoil. {| style="border-spacing:0;" | style="border-top:…'

New page

Tutorial: Creating and Meshing an airfoil in Gmsh

Script and Narration: Gautam Sharma

Keywords: Gmsh, Meshing, airfoil.

{| style="border-spacing:0;"
| style="border-top:0.05pt solid #000000;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| <center>Visual Cue</center>
| style="border:0.05pt solid #000000;padding:0.097cm;"| <center>Narration</center>

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 1
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Hello and welcome to the spoken tutorial on '''Creating and Meshing an airfoil in Gmsh'''

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 2 : Learning Objectives

| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| In this tutorial we will learn

* How to create an airfoil using Gmsh
* How to mesh the created airfoil

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 2: Pre-requisite
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| To practice this tutorial the user should have basic knowledge of '''Airfoil '''and '''Gmsh.'''

If not, for Gmsh kindly refer the tutorial on '''Installing and running Gmsh '''on the '''spoken tutorial''' website.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 3:

System Requirement
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| To record this tutorial, I am using

* '''Ubuntu Linux''' Operating system version 13.10. and
* '''Gmsh''' version 2.8.4

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 4: About Airfoil

| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let me introduce you to aerofoil.

Aerofoils are streamline shaped wings which are widely used in airplanes and turbo machinery.

These shapes are such that the drag force is a very small as compared to the lift.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Show the airfoil
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| This is the geometry of an airfoil.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide 5 :

The dat file

Download the dat file and Python script

Open browser

Download the files

Go to desktop
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The predefined coordinates for airfoil are available in simple text file with .dat extension.

We will download the .dat file and python script from this url:

[http://community.dur.ac.uk/g.l.ingram/download.php http://community.dur.ac.uk/g.l.ingram/download.php]

I will open the browser now.

In the address bar type in the url as shown in previous slide.

Download the '''naca5012xyz.dat''' file and the python script '''dat2gmsh.py''' and save on the '''desktop.'''

Go to the '''desktop'''. Here you can see both the files.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Open '''naca5012xyz.dat''' file

Open Python script
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let me show you the .dat file.

This file contains the calculated X and Y coordinates of each point that defines the airfoil.

We need the X, Y and Z coordintes in Gmsh acceptable format. This can be done manually but is time consuming.

We will use a python script to do it.

Let me show you the script.

This is the python script. Close the script.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Open the terminal

| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Press '''alt ctrl''' and '''T '''key simultaneously to open the '''terminal.'''

In the terminal type '''cd space Desktop''' to change the present working directory to desktop.

Type '''ls '''and press enter. You can see both the files.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Run the python Script

python dat2gmsh.py naca5012xyz.dat
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now type '''python''' space '''dat2gmsh.py''' space '''naca5012xyz.dat'''

This creates a new file with '''.geo''' extension which contains the coodinates in '''gmsh '''acceptable format.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Open naca5012xyz.dat.geo
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Let me show you the file.

The '''nac_lc''' is the characterstic length which is defined as 0.005

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Open file in gmsh

Zoom in at the tail

Close the gmsh
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| In the terminal type gmsh space '''naca5012xyz.dat.geo '''and press enter.

This opens the gmsh with the airfoil.

Zoom in by scrolling at the tail of the airfoil. You will note that the aerofoil has an open trailing edge.

Close the '''gmsh'''.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Open the .geo file with text editor again

Add the point
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Go back to the .'''geo''' file. Scroll down to the bottom.

We will add a new point at the tail to complete the aerofoil.

Type:

'''Point(1046) = { 1.005, -0.0005, 0.00000, nac_lc};'''

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Modify the '''spline'''

Open '''.geo''' file in gmsh
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Modify the '''spline '''to add the new point

'''Spline(1000) = {1000:1046,1000};'''

Save and close the file.

In the terminal repeat the same command by pressing the '''up '''key. You will note that the edge is joined.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Set up a boundary around the airfoil

Enter the points as

(4 3 0)

(4 -3 0)

(-4 -3 0)

(-4 3 0)
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now we will make a boundary for the airfoil.

Go to '''Geometry > Elementary entitites > Add '''and click on Points. Enter the coordinates of the boundary as:

(4 3 0)

(4 -3 0)

(-4 -3 0)

(-4 3 0)

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Join the points by Straight lines
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now join the points with straight line

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Define the surface
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Click on '''Plane surface. '''Select the surface boundary

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Select the '''aerofoil'''

Press e to end selection
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Zoom in and select the '''airfoil''' as the hole boundary.

Click '''e '''to end selection. We have our surface

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Extrude the surface
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now we will extrude the surface to make it 3D

Go to''' Translate '''and click on '''Extrude Surface.'''

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Enter the coordinates for Z direction

Press '''e''' to end selection

Move the geometry
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Since we want to extrude the surface in positive Z direction.

The Z component is kept as 1

Select the boundary of the surface.

Press '''e '''to end selection.

Use the left click of the mouse to move the geometry. You can see that the 3D geometry.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Generate the mesh

Go to Mesh>3D
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now we will do the meshing. Gmsh automaticaly generates the mesh of the defined geometry.

Scroll down to '''Mesh '''and click on '''3D. '''The mesh has been generated.

You may note that the mesh is finer near the airfoil and gets coarse as it goes towards the boundary.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Refine the mesh
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| We can also refine the mesh by clicking on the '''Refine by Splitting '''in the mesh menu.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Save you work
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Now let us save our work.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Click on save as
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Go to '''File''' menu and click on '''Save mesh.'''

We will name our file as '''airfoil.msh'''

Note that here '''msh '''stands for the file type '''mesh'''.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide : Assignment
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| This brings us to the end of the tutorial.

As an '''assignment''' try creating airfoil by using different dat file for different airfoil shapes.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide : Summary

| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| In this tutorial we learnt :

* To create an Airfoil in Gmsh.
* To mesh in Gmsh.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide :

About Spoken tutorials
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Watch the video available at this URL:

http://spoken-tutorial.org/What_is_a_Spoken_Tutorial

It summarizes the Spoken Tutorial project.

If you do not have good bandwidth, you can download and watch it.

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide:

About Spoken tutorials
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| The Spoken Tutorial Project Team

-Conducts workshops using spoken tutorials

-Gives certificates to those who pass an online test

-For more details, please write to

contact@spoken-tutorial.org

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| Slide:

Acknowledgement

| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| Spoken Tutorials are part of Talk to a Teacher project,

It is supported by the National Mission on Education through ICT, MHRD, Government of India.

This project is coordinated by http://spoken-tutorial

More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro

|-
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:none;padding:0.097cm;"| About the contributor
| style="border-top:none;border-bottom:0.05pt solid #000000;border-left:0.05pt solid #000000;border-right:0.05pt solid #000000;padding:0.097cm;"| This is Gautam Sharma from IIT BOMBAY signing off.

Thanks for joining.

|}

@@ Line 28: / Line 28: @@
 |-
-| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Slide 2: Pre-requisite
+| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Slide 2:
-| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| To practice this tutorial the user should have basic knowledge of '''Airfoil '''and '''Gmsh.'''
-−
-−
-If not, for Gmsh kindly refer the tutorial on '''Installing and running Gmsh '''on the '''spoken tutorial''' website.
-−
-|-
-| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Slide 3:
 System Requirement
@@ Line 44: / Line 37: @@
 |-

OpenFOAM/C3/Creating-and-Meshing-aerofoil-in-Gmsh/English - Revision history

Nancyvarkey at 06:11, 18 December 2015

Gautam at 20:31, 7 August 2014

Gautam at 07:55, 7 August 2014

Gautam: Created page with 'Tutorial: Creating and Meshing an airfoil in Gmsh Script and Narration: Gautam Sharma Keywords: Gmsh, Meshing, airfoil. {| style="border-spacing:0;" | style="border-top:…'